Javascript string assignment to key-value string

Question

I have the following code:

var inputString ={"Key1":"Planes","Key2":"Trains","Key3":"Cars","Key4":"Caoch","Key5":"Cycles","Key6":"Bikes"}

var value = inputString ["Key3"];
alert(value);

The above code works fine, notice that the variable inputString is assigned everything between the curly braces. I'm a js novice but I think that is a convention to indicate some sort of object. That kind of string assignment looks strange to me, but it works as demonstrated above.

My issue is when I try to assign the variable inputString to string literal, as follows:

var inputString2 ='{"Key1":"Planes","Key2":"Trains","Key3":"Cars","Key4":"Caoch","Key5":"Cycles","Key6":"Bikes"}'

var value = inputString2 ["Key3"];
alert(value);

The above code returns undefined, why?

I'm sure someone with a deep understanding of javascript can explain this to me.

Thank you

You need to use eval on that string.... j/k (don't do that) look into json.js json.org/js.html — Kevin Bowersox
– Kevin Bowersox, Commented May 9, 2013 at 15:54
this "some sort of object" is actually called an object literal, the second one is just a string literal, most probably a string dump of a JSON object — Aprillion
– Aprillion, Commented May 9, 2013 at 16:01

PSL · Accepted Answer · 2013-05-09 15:51:28Z

5

That is because it is not object it is just a string.

var inputString2 ='{"Key1":"Planes","Key2":"Trains","Key3":"Cars","Key4":"Caoch","Key5":"Cycles","Key6":"Bikes"}'

You need to remove quotes around your json. It should be like this.

 var inputString2 ={"Key1":"Planes","Key2":"Trains","Key3":"Cars","Key4":"Caoch","Key5":"Cycles","Key6":"Bikes"}

If you get it as string. Use JSON.parse

 var convertedJson =  JSON.parse(inputString2);
var value = convertedJson ["Key3"];
alert(value);

See JSON.parse

answered May 9, 2013 at 15:51

PSL

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3 Comments

Karthik Over a year ago

Hi PSL, is there a way to turn inputString2 from a string into an object, so it can work?

PSL Over a year ago

Use JSON.parse(inputString2)

David Thomas Over a year ago

Don't wrap the curly braces with quotes.

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